Phileurus truncatus (Palisot de Beauvois, 1806)

Arguez, Katherine M., Moore, Matthew R. & Branham, Marc A., 2017, Description of the larva and pupa of Phileurus truncatus (Palisot de Beauvois, 1806) (Coleoptera: Scarabaeidae: Dynastinae: Phileurini) with a key to described third instars of New World Phileurini, Zootaxa 4363 (2) : -

Phileurus truncatus (Palisot de Beauvois, 1806)

Pupa

( Figs 11–13 )

Material examined. Two pupae with the following data: “ FLORIDA: Alachua Co/Gainesville; turkey oak;/larva 7-II-1976 /pupa 15-IV-1976 / Scarabaeidae Phileurus / truncatus /P.M. Choate collr.”; “ FLORIDA: Alachua Co./ Gainesville; NATL, I- 2016./coll. Gabe Somarriba”.

Description. Length 42–44 mm; greatest width 18–20 mm ( Figs 11–13 ). Body elongate, oval, stout, exarate. Color dark reddish brown. Entire body with very fine, small, golden setae. Head: Surface glabrous, bent sharply beneath thorax, mouthparts directed ventrally; antennae, labrum, mandibles, maxillary, and labial palps discernible; antennal thecae expanded, stout, with apices rounded. Compound eyes sunken, visible, with 2 tubercles between eyes. Thorax: Pronotal surface glabrous. Form transverse, with wide, anteromedial, rounded apex. Mesonotum and metanotum well differentiated. Elytral and posterior wing thecae closely appressed, curved ventrally around body; elytral thecae extending to end of abdominal segment I; posterior wing thecae extending to middle of abdominal segment III. Protibia with 3 distinct teeth on external edge. Mesotibia and metatibia with 3 swellings at apices; characters indicative to spines and spurs seen in adults, with the external swelling most likely the spine and the 2 inner swellings most likely the 2 apical spurs (1 spine on each tibia in adults). Abdomen: Segments III–X (ventral view) well defined. Segment VII slightly long than preceding segment and segment VIII 0.25 times longer than segment VII; segments VIII and IX fused. Segments I–X (dorsal view) with well-defined, dioneiform (gin trap) organs between segments I–II, II–III, III–IV, IV–V, V–VI, and VI–VII. Pleural lobes rounded. Spiracle I ovate, covered by wing thecae, more broadly opened than spiracles II–IV; spiracles II–IV ovate, prominent, each with strongly sclerotized peritreme; spiracles V–VI less sclerotized compared to I–IV; spiracles V–VIII closed. Abdominal apex rounded, with fine, short setae.

Diagnosis. Third-instar P. truncatus will key out to the terminal 4th couplet in the phileurine larval key to species of Ibarra-Polesel et al. (2017). This is based on the lack of anterior frontal setae and the presence of an angulate margin on the left side of the labrum in P. truncatus . In the modified key below, the 4th couplet now separates Phileurus and Hemiphileurus species based on the number of dorsal sensory spots on the terminal antennomere. Phileurus truncatus keys to the 5th couplet where it is separated from H. elbitae Neita & Ratcliffe, 2010 by the size of the abdominal spiracles and the number of maxillary stridulatory teeth.

The third-instar Phileurus truncatus examined for this study lack long, thin anterior frontal setae. The presence of anterior frontal setae, along with similar sized tarsal claws on all the legs, are characters shared between the other known third instars of Phileurus species ( Ibarra-Polesel et al. 2017). The lack of long, thin anterior frontal setae in P. truncatus thus broadens the diagnosis for the genus. Examined specimens of third-instar P. trunctatus do have setose punctures across the anterior margin of frons. However, these punctures are sporadically arranged and the short, stout setae in them does not reach past the margin of the punctures. We do not think that these punctures are associated with the anterior frontal setae found in other phileurine larvae.

Figures

FIGURES 11–13. Phileurus truncatus, pupa.11, Dorsalhabitus; 12, ventral habitus; 13, lateral habitus.